1. Technical Field of the Invention
This invention relates to a key top assembly which is integrated with a film and is built into the input portion of equipment such as a telephone, a mobile communications device, an acoustic equipment, a television set, a video cassette recorder, a facsimile machine, a copying machine, and an on-vehicle device.
2. Related Art
In conjunction with the fact that electric and electronic devices have become compact and portable, there is a demand for smaller, thinner and lighter push-button switches for use in the operational portions of such devices.
By way of a measure to meet such a demand is known a key top assembly integrated with a film as shown in FIG. 7, wherein required characters and symbols are printed on the upper surface or on the undersurface of a transparent or translucent flexible resin film 17, and a key top body 18 is attached, by a technique such as fusion or bonding, to the interior of each recess formed by the above-mentioned resin film 17 bent upward. The arrangement of this key top assembly integrated with a film, as it is mounted on a device, is such that each key top body 18 is placed separately from others inside one of the frames of a mounting 19.
In recent years, as regards push button switches used in carrying out a retrieval function of devices such as cellular telephones and portable terminals, there has been a growing demand for a push button switch designed in such a way that a core key top is placed inside an annular key top. In the event that a key top assembly thus designed is mounted on a pertinent device, then it follows that an annular key top and a core key top are placed inside a single frame, with the result that the clearance between the two adjacent key tops is very small.
Problems to be Solved by the Invention
However, in the case of a prior art key top assembly integrated with a film, wherein the clearance between adjacent key tops is small, when one of the key tops is pressed, at least one of the adjacent key tops becomes interlocked, thus presenting a problem. For the purpose of avoiding the interlocking of adjacent key tops, the two following types are available: a key top assembly integrated with a film as shown in FIG. 8, wherein a groove 20 is formed at approximately the center of that portion of a resin film which is located between adjacent key tops; and a key top assembly integrated with a film as shown in FIG. 9, wherein slits 22 are machined in those portions of a resin film which are located between adjacent key tops.
It is true that the interlocking of key tops can be prevented in the case of the above-mentioned types, but it is necessary that the clearance between adjacent key tops be rendered large. Therefore, in the case of an arrangement wherein a plurality of key tops are placed inside one of the frames of a mounting, those portions of a resin film which are located between adjacent key tops are exposed, resulting in a crude appearance.
Means To Solve the Problems
The present invention, which seeks to solve the above-mentioned problems, provides a key top assembly integrated with a film in which a plurality of key tops can be placed inside one frame and which has the following features: clearances between adjacent key tops are rendered small; no key top interlocks with any other key top; and a good appearance is presented.
Namely, in the case of this key top assembly integrated with a film, a core key top is placed inside a circumferential outer key top, and that portion of a resin film which connects the body of the above-mentioned key top to the body of the above-mentioned core key top is formed into a bent shape in such a way that the lower end of this bent portion is located at a position lower than the lower ends of the areas where the above-mentioned resin film is bonded to the bodies of the above-mentioned two key tops.
Furthermore, as regards this key top assembly integrated with a film, the interior portion of the base of the above-mentioned circumferential outer key top is cut out, resulting in the interior portion of the above-mentioned base being formed at a position higher than that of the exterior portion of the above-mentioned base.
Moreover, as for this key top assembly integrated with a film, the body of the above-mentioned circumferential outer key top is annular.